Please fill in your details to download the Table of Contents of this report for free. We also do customization of these reports so you can write to us at mi@fibre2fashion.com in case you need any other additional information.

Trends to dye for

Sustainability in the textiles and apparel industry is determined to a large extent by the way the textile processing sector is shaping up. It works both ways: sustainability makes demands on processing, and the latter in turn dictates the direction that industry is going to take, writes Subir Ghosh.

Just talking about trends is one thing; seeing them implemented is quite another. The most far-reaching, yet possibly one of the least talked about, was the crackdown of the Chinese government on polluting factories. Numbers do not easily trickle out of China, but whatever did about a year back ought to have had the global textiles and apparel industry discussing it furiously. In October 2017, many international news establishments reported that over 80,000 polluting units across 30 provinces had been shut down in China for violating environmental laws and norms. Most of these were one cog or another of the supply chain of the global textiles and apparel industry.

In May this year came more reports-this time about 40 per cent of manufacturing facilities being hit down in the country, with the textiles industry bearing the brunt of the government's measures. Within the industry, it was the dyeing and printing facilities that have been affected the most. It is being said that life in entire towns have come to a standstill as a result. This is so because that is how the Chinese manufacturing works-entire towns or townships are built around specific sectors of manufacturing. But that is not all; the textile scouring, bleaching, dyeing and other closely-related finishing processes that use heated water now have to do so with clean, gas-fired boilers. China aims to cut the concentration of PM2.5 hazardous fine particle matter to 35 micrograms per cubic metre by 2035 from 47 micrograms per cubic meter in 2016. The penalties in 2017 ranged from heavy fines to rigorous imprisonment.

Meanwhile, the supply chains of innumerable global brands have slowed down, and many have migrated their manufacturing facilities to other less-regulated countries.

While many in other countries would gloat over the fact that manufacturing is shifting out of China to their own, there is as well a different lesson to be learnt here: that sooner or later countries are going to crack down. It would also become difficult for big brands to justifying moving out of China just because that country is enforcing environmental laws. One cannot keep harping on the sustainability string by turning one's back on countries that crack down on environmental violators.

But wait, there is another angle to the story. It is true that sustainability compulsions are slowly beginning to drive most industry trends, and it is also true that most debates on the subject hitherto have been confined to an overview level, with precious little talk about how things are working out with the less glamorous cogs of the supply chain: the processing sector. Yet, the processing sector itself is made up of many sub-sectors: desizing, scouring, bleaching, mercerising, singeing, raising, calendering, shrinking/sanforsing, dyeing, and finally printing. All these sub-sectors deal with matters

that are too technical and insipid to figure in the animated discussions at glitzy fashion events. That is fallacious since at the core of sustainability issues pertaining to the textiles and apparel industry lies the processing sector. It is the processes and trends here that is going to make or break the sustainability drive.

It is not fair to discount any of the sub-sectors in terms of importance, yet it would still be fair to say that two of these have the maximum bearing on the industry: dyeing and printing.

Dye Another Day

In the beginning, everything was "natural."

The earliest dyed flax fibres are said to have been used in Europe, with evidence to that effect being found in a prehistoric cave in Georgia dating back to 34,000 BC. Traces of red dyes, possibly from ochre, an iron oxide pigment derived from clay, have been found in a Neolithic settlement at Catalhoyuk in southern Anatolia. Eastwards, in China, dyeing with plants, barks

and insects are reckoned to be more than 5,000 years old. Here in the sub-continent, remains of cotton dyed with a vegetable dye have been discovered at a Mohenjo-daro excavation site in Sindh, Pakistan.

Dyeing trends remained so till an 18-year-old at the Royal College of Chemistry in London by the name of William Henry Perkin was posed a challenge by his professor to synthesise quinine. The year was 1856, and the textiles-driven Industrial Revolution was at its peak in England. Perkins, working at a garden hut with two friends, ended up with a black solid, which when cleaned with alcohol yielded a solution that was curiously purple in colour. Perkin of course failed in his attempt to find that elusive cure for malaria, but he went on to patent this chemical that they called mauveine. Till this point, all dyes used for colouring cloth were natural substances, all of which were either labour-intensive or simply expensive. Perkin found that this accidental by-product could be used as a dye. Better still, the source material need not be cultivated-it was available in plenty as a by-product of coal tar.

Perkin patented the dye in August 1856, raised some capital from his father and started cheap manufacturing, initially adapting it to cotton as also the silk that he had initially experimented with. Within a decade or so, the cost-intensive natural dyes went out of vogue. Perkin's was the first synthetic dye. It was fast, easy to produce, and it was only natural that it would change the textiles industry forever. Since then, all dyeing innovations and inventions have been extensions of Perkin's work.

The definition of dyeing has not changed, and as Wikipedia describes: "Dyeing is the application of dyes or pigments on textile materials such as fibres, yarns, and fabrics with the objective of achieving colour with desired fastness. Dyeing is normally done in a special solution containing dyes and particular chemical material. Dye molecules are fixed to the fibre by absorption, diffusion, or bonding with temperature and time being key controlling factors. The bond between dye molecule and fibre may be strong or weak, depending on the dye used. Dyeing and printing are different applications; in printing colour is applied to a localised area with desired patterns and in dyeing it is applied to the entire textile."

The realities, however, changed. Environmental awareness during the time of Perkin's discovery was still a hundred years off; industrialists thought no more than production, and people cared not a fig about how their garments were produced. Today, matters have almost turned a full circle. What had once revolutionised garment manufacturing is now at the core of sustainability issues, and much of the research and development (R&D) work in industry now focuses either on finding new dyes/ pigments that have a minimal footprint on the environment, or on finding that new, elusive, dye that is natural.

That, as it were, is easier said than done. By their very nature, natural dyes are extracted mostly from plants and are expensive to produce. They also need to come in significantly larger quantities to create the same depth in colour, which in any case washes off gradually. Moreover, it takes roughly 13 acres of land to grow enough dye for just one acre of cotton. With biotic pressures on land increasing by the day and arable land becoming as difficult to come by, the usage of natural dyes does not still make for either a commercial or sustainable proposition. Not to speak of the water that cotton requires for cultivation.

Such ground truths, in turn, shift the pressure and responsibility on researchers. Much of the ongoing research initiatives are in their infancy, and not much is known about whether the new innovations and inventions have possibilities for mass production. One potential gamechanger was announced earlier this year by Norwegian textiles company Expert Fibres. IndiDye, the solution developed by the company which has operations in Oslo and Shanghai, is a dyeing technology that combines natural colours and ancient dyes with an innovative new ultrasonic fibre-dyeing process.

According to the company, "The dyeing is implemented at fibre level before the IndiYarns are spun. Dye-tanks are filled with batches of fibre together with liquid natural dyestuff and exposed to ultrasonic pressure waves that push the colour pigments into the core of the fibre. This is what gives the unique IndiDye colour fastness never before achieved with natural plant dyes-without adding chemical fixation agents. The IndiDye dyeing technology uses natural liquid dyes in a dyeing process that completely eliminates waste water, thus significantly reducing water consumption.

"Through lower dyeing temperatures and shorter dyeing times, IndiDye also offers measurable improved efficiency in energy and emissions." The company claims that the plantations where the plants for the dyestuffs are grown only use natural fertilisers. Crops are rotated, thus improving soil conditions, rotations, and pesticides are avoided. Besides, farming is done in areas with natural abundance of water, limiting artificial irrigation. The dyeing mills are close to the farms to reduce transportation impacts.

Besides, IndiDye products provide end-users with traceability through QR-codes that identify the natural dye-batch which the end product originates from. But whether IndiDye can turn the Perkin discovery on its head is too early to be asserted. So far, it remains just another discovery. It has not taken the world by storm as yet, and most industry talk is still confined to R&D work that has been going on for years.

There are other potential game-changers in the market, like Dutch company DyeCoo. Its CO2 technology is the world's first 100 per cent water-free and chemical-free textile processing solution. The technology uses reclaimed CO2 as the dyeing medium in a closed loop process. "When pressurised, CO2 becomes supercritical (SC-CO2 )-a phase between a liquid and a gas. In this state CO2 has a very high solvent power, allowing the dye to dissolve easily. Thanks to the high permeability, the dyes are transported easily and deeply into fibres, creating vibrant colours."

The company claims that CO2 dyeing does not need added process chemicals to dissolve dyes. Its technology uses 100 per cent pure dyes and with more than 98 per cent uptake, there is hardly any wastage. And since there are no chemicals or water involved, the question of waste-water treatment does not arise. The CO2 itself is reclaimed from existing industrial processes, recycling 95 per cent of it in a closed loop system. DyeCoo says that the results can now be seen on an industrial scale, and the short batch cycles, efficient dye use, no wastewater treatment all lead to reduced operating costs.

The company is assertive, and says on its website: we can dye fabric in the middle of the Sahara.

But once again, DyeCoo has been around for a bit with its fantastic technology, and is yet to change the textiles world. A little streamlined surfing on the internet will throw up innumerable technologies and solutions-not all of them like that of IndiDye or DyeCoo. All those would collectively beg the same question: is the industry way too slow and lethargic in changing itself?

In some ways, maybe yes. On the other hand, there are companies that are trying their own hand at sustainable processing. Levi Strauss & Co, for instance, is working on a new operating model that replaces labour-intensive manual finishing techniques with an automated digital laser-based system.

It is called Project Future-Led Execution or Project FLX, and shortens the time to market and cuts chemicals from the finishing process. The model has been developed in-house by designers, developers, chemists, and engineers at Levi Strauss & Co's Eureka Innovation Lab.

As of now, finishing jeans by hand to produce that look of vintage denim requires 18-20 steps per finish. But now, laser technology reduces the number of steps to three. The company is still scaling the model across its denim supply chain, and working with vendors and retail partners. The company, which wants to achieve zero discharge of hazardous chemicals by 2020, wants to roll out Project FLX by that time.

The examples of DyeCoo, IndiDye and Levi Strauss are just that: examples. What they collectively show is that it can be done. What the Chinese crackdown shows is that consequences are inevitable. Of course, those would vary from one country to another.

The Fine Print

Printing as a form of textile processing is similar to dyeing, with many defining printing as a form of localised dyeing. The elementary difference is that printing is done in a pre-determined manner. For reasons of similarity, issues-and therefore, trends too-concerning printing are not very different.

Most of the developments in the printing phase of textile processing have to do with the constant refining of digital printers and printer-head technology. Digital textile printing, except in situations where screen-printing is a more feasible alternative, has forged way head. But looking at it as an open and shut case would be rendering the subject way too simplistic. That's because digital printing is only one form of textile printing, and is more relevant to ready-to-wear garments.

The Wikipedia entry on the digital textile printing defines it thus: "Digital textile printing (DTP) is described as any inkjet-based method of printing colourants onto fabric. Most notably, DTP is referred to when identifying either printing smaller designs onto garments (t-shirts, dresses, promotional wear; abbreviated as DTG, which stands for direct-to-garment) and printing larger designs onto large format rolls of textile. The latter is a growing trend in visual communication, where advertisement and corporate branding is printed onto polyester media. Examples are: flags, banners, signs, retail graphics."

But printing is much more. "Textile printing is the process of applying colour to fabric in definite patterns or designs. In properly printed fabrics the colour is bonded with the fibre, so as to resist washing and friction. Textile printing is related to dyeing but in dyeing properly the whole fabric is uniformly covered with one colour, whereas in printing one or more colours are applied to it in certain parts only, and in sharply defined patterns. In printing, wooden blocks, stencils, engraved plates, rollers, or silkscreens can be used to place colours on the fabric. Colourants used in printing contain dyes thickened to prevent the colour from spreading by capillary attraction beyond the limits of the pattern or design."

Nonetheless, DTP has changed the way the last few stages of the supply chain had been working all this while. Today, a wider variety of designs are possible, delivery times have been shortened, and considerable amount of waste has curtailed from the phase. All this also means a lot of money, and practically zero discharge of effluents and chemicals. Other forms of printing can barely compete.

There is another impact that DTP has: it has a significance on many of the earlier phases of processing. For inkjet printing to yield the desired results, a highly effective pre-treatment is a must. Therefore, the fabric has to be singed correctly to remove surface fibres that can otherwise bring down the quality of fabric printing quality since such fibres can graze the print head and block the nozzles.

The stages of desizing, scouring and bleaching too have to be streamlined to remove impurities and render the fabric with a quality of uniform absorbency and whiteness. With the depth of colours being a deciding element, mercerisation needs to ensure that the colour depth is increased. So, if a fabric is to be digitally printed, the preceding stages of processing have to take this factor into account. Besides, in screen printing the colours would be applied as high viscosity pastes. But DTP requires thin ink formulations, and the colours must be of small particle size since those would otherwise block the nozzles.

Every category of the fashion industry has either already embraced digital in some ways, or has gone whole hog. From high-end apparel and fast fashion to home textiles and apparel accessories, the digital form of printing is changing the way those categories work.

The traditional forms of printing like hand-block printing, roller-cylinder-machine printing and screen printing remained dominant till the 1990s when piezoelectric drop-on-demand printing technology emerged as a new alternative. For close to two decades, this technology remained on the sidelines, not being able to score on any of the fronts desired-cost, speed, quality and effectiveness. But the traditional textile machinery suppliers of Italy and Japanese printhead manufacturers changed all that. Once they were able to understand the properties of different fibres, higher speed and better resolution began to show in the new digital printers. This started with the adoption of dye sublimination roll-to-roll inkjet printing (also called transfer printing). The designs were first printed on paper and then transferred to the fabric through a heat press process. This process is still used for soft signage applications and sportswear. But the area which has seen the maximum transformation is DTG printing. Advances on two fronts, in turn, are determining the way DTP itself progresses: print-heads and inks.

Industry association FESPA says on its website: "In many respects the print-head is the heart of an inkjet printer, directly responsible for placing each individual drop of ink on the substrate. Inkjet printheads are marvels of modern engineering, able to precisely place thousands of drops of ink of differing sizes exactly where needed. There are several approaches to designing printheads but by far the most common for wide-format inkjet is drop-on-demand piezo." That about sums up the idea; but from the purely technological point of view, advances are being made practically every single day.

The other aspect-pigments-is also changing fast. A blog post on the IMI Europe website remarks: "The pigment ink market for textile inkjet printing is emerging rapidly. Pigment inks have a lot of benefits such as a high colour strength and high light resistance. They are considered as 'universal inks' because they can be applied directly on a large range of textile substrates without sophisticated or environmentally unfriendly pre- or post-treatments. Waterbased pigment inks usually require only simple dry heat for a few minutes as a post-treatment process and no special pre-treatment. However, the development of water-based pigment inks is highly challenging in terms of colloidal dispersion stability, jetting reliability and polymer binder chemistry." Even this technology dictates how some of the preceding stages of processing should work. As the same post points out, "For most digital textile inkjet inks (besides pigment inks), a proper pre-treatment of the substrate is a necessity, e.g. in order to minimise lateral ink bleeding and to maximise colour definition and colour intensity."

Both these aspects of digital printing indicate one crucial point: the preceding stages of textile processing have to undergo changes, perhaps constantly, in order to cater to this form of printing. In other words, the textile processing sector remains in a flux.

Comments

Disclaimer

Responsibility:

Fibre2fashion.com does not warrant or assume any legal liability or responsibility for the excellence, accurateness, completeness, legitimacy, reliability or value of any information, product or service represented on Fibre2fashion.com. The information provided on this website is for educational or information purposes only. Anyone using the information on Fibre2fashion.com, does so at his or her own risk, and by using such information agrees to indemnify Fibre2fashion.com, and its content contributors from any and all responsibility, loss, damage, costs and expenses (including legal fees and expenses), resulting from such use.

No Endorsement:

Fibre2fashion.com does not endorse or recommend any article on this site or any product, service or information found within said articles. The views and opinions of the authors who have submitted articles to Fibre2fashion.com belong to them alone and do not reflect the views of Fibre2fashion.com.

Submit your Request

If you wish to reuse this content on web, print or any other form, please seek for an official permission by writing to us on editorial@fibre2fashion.com

Knowledge

Fibre2Fashion has a diverse global readership, and delivers unique, authoritative and relevant content. Drawing on the expertise and credibility that we have built over the years and contextualising them with our in-depth research studies, we produce authentic news, articles, reports, interviews and interactive explainers through the F2F Magazine and compendiums, among others, which help readers stay abreast with the industry trends.